The phase-locked mean impulse response of a turbulent channel flow

We describe the first DNS-based measurement of the complete mean response of a turbulent channel flow to small external disturbances. Space-time impulsive perturbations are applied at one channel wall, and the linear response describes their mean effect on the flow field as a function of spatial and temporal separations. The turbulent response is shown to differ from the response a laminar flow with the turbulent mean velocity profile as base flow.Comment: Accepted for publication in Physics of Fluid

Changing time and emotions

In this paper, we consider that our experience of time (to come) depends on the emotions we feel when we imagine future pleasant or unpleasant events. A positive emotion such as relief or joy associated with a pleasant event that will happen in the future induces impatience. Impatience, in our context, implies that the experience of time up to the forthcoming event expands. A negative emotion such as grief or frustration associatedwith an unpleasant event thatwill happen in the future triggers anxiety. This will give the experience of time contraction. Time, therefore, is not exogeneously given to the individual and emotions, which link together events or situations, are a constitutive ingredient of time experience. Our theory can explain experimental evidence which shows that people tend to prefer to perform painful actions earlier than pleasurable ones, contrary to the predictions yielded by the standard exponential discounting framework.experience of time ; emotions ; impatience ; anxiety ; discount factor ; time preference

"If you have the flu symptoms, your asymptomatic spouse may better answer the willingness-to-pay question". Evidence from a double-bounded dichotomous choice model with heterogeneous anchoring.

The small sample size of contingent valuation (CV) surveys conducted in patients may have limited the use of the single-bounded (SB) dichotomous choice format which is recommended in environmental economics. In this paper, we explore two ways to increase the statistical efficiency of the SB format: (1) by the inclusion of proxies in addition to patients; (2) by the addition of a follow-up dichotomous question, i.e. the double-bounded (DB) dichotomous choice format. We found that patients (n=223) and spouses (n=64) answering on behalf of the patient had on average a similar willingness-to-pay for earlier alleviation of flu symptoms. However, a patient was significantly more likely to anchor his/her answer on the first bid as compared to a spouse. Finally, our original DB model with shift effect and heterogeneous anchoring reconciled the discrepancies found in willingness-to-pay statistics between SB and DB models in keeping with increased statistical efficiency.Contingent valuation; double-bounded dichotomous choice; Patient; proxy; anchoring; structural shift; influenza

Dynamic cointegration and relevant vector machine: the relationship between gold and silver

We use the Relevant Vector Machine, a technique of supervised learning introduced by Tipping (2001), to conduct a dynamic cointegration analysis on the time series of the price of gold and silver over the period 1971-2004. Unlike the results of traditional cointegration analysis, this study reveals that there is a dynamic long run relationship over the whole periodDynamic cointegration, relevant vector machine

Designing the Financial Tools to Promote Universal Access to AIDS Care.

We argue that reluctance to invest in drug treatments to fight the AIDS epidemics in developing countries is largely motivated by severe losses occurring from the future albeit uncertain appearance of a curative vaccine. We design a set of securities generating full insurance coverage against such losses, while achieving full risk-sharing with vaccine development agencies. In a general equilibrium framework, we show that those securities are demanded to improve social welfare in developing countries, to increase current investment in treatments and the provision of public goods. Even though designed foi AIDS, those securities can also be applied to other epidemics such as Malaria and Tuberculosis.HIV/Aids funding, security design, therapeutic innovation,health underinvestment, HIV/Aids vaccine

Contingent Valuation of Competing Public Sector Programmes: An Experiment of Single versus Joint Evaluation

In this paper, we compare single and joint evaluation (JE) of competing public sector programmes in a contingent valuation exercise. Using survey data aimed at evaluating WTP for cancer interventions (n = 2628), we disantangle two types of effects of JE: informational effects and sequence effects. By the former, wemean: by presenting different programmes to respondents, they will acquire more information on each programme than they would if each programme was valued in isolation. Sequence effects are underisable and induced by the JE exercise itself: changing the order of the valuation sequence induces different WTP values.Our results show that there are informational effects but no sequence effects. We therefore argue that JE approaches can be added to the armoury of techniques aimed at designing better survey instruments in a way that induces informational effects without incurring problems of sequencing.Single Evaluation; Joint Evaluation Willingness to Pay; Contingent Valuation; Priorities Setting

Do people always pay less than they say? Testbed laboratory experiments with IV and HG values

Hypothetical bias is a long-standing issue in stated preference and contingent valuation studies – people generally overstate their preferences when they do not experience the real monetary consequences of their decision. This view, however, has been challenged by recent evidence based on the elicitation of induced values (IV) in the lab and homegrown (HG) demand function from different countries. This paper uses a two experiments design to assess the extent and relevance of hypothetical bias in demand elicitation exercises for both IV and HG values. For testbed purpose, we use a classic second-price auction to elicit preferences. Comparing the demand curve we elicit in both, hypothetical bias unambiguously (i) vanishes in an induced-value, private good context, and (ii) persists in homegrown values elicitation context. This suggests hypothetical bias in preference elicitation appears to be driven by “preference formation” rather than “preference elicitation”. In addition, companion treatments highlight two sources of the discrepancy observed in the HG setting: the hypothetical context leads bidders to underestimate the constraints imposed by their budget limitations, whereas the real context creates pressure leading them to bid “zero” to opt out from the elicitation mechanism. As a result, there is a need for a demand elicitation procedure that helps subjects take the valuation exercise sincerely, but without putting extra pressure on them.Auctions; Demand revelation; Experimental valuation; Hypothetical bias